Tn5044-Conferred Mercury Resistance Depends on Temperature: the Complexity of the Character of Thermosensitivity

Authors: Kholodii G.¹; Bogdanova E.²

Source: Genetica, Volume 115, Number 2, June 2002 , pp. 233-241(9)

Publisher: Springer

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Abstract:

Escherichia coli K12 containing the transposon Tn5044 mer operon (merR, T, P, C, and A genes) is resistant to mercuric chloride at 30°C but sensitive to this compound at 37–41.5°C. We have studied the mechanism underlying the temperature-sensitive nature of this mercury resistance phenotype, and found that the expression of the Tn5044 merA gene coding for mercuric reductase (MerA) is severely inhibited at non-permissive temperatures. Additionally, MerA showed a considerably reduced functional activity in vivo at non-permissive temperatures. However, the temperature-sensitive character of the functioning of this enzyme in cell extracts, where it interacted with one of the low-molecular weight SH compounds rather than with the transport protein MerT (as is the case in vivo), was not apparent. These data suggest that the temperature-sensitive mercury resistance phenotype should stay under control at two stages: when the merA gene is expressed and when its product interacts with MerT to accept the mercuric ion.

Keywords: Hg(II) uptake system; MerA; mercuric reductase; mer operon; MerP; MerT; SH compound; Tn5041; Tn5044; transport protein; transposon

Language: English

Document Type: Research article

Affiliations: 1: Institute of Molecular Genetics, Russian Academy of Sciences, 123182, Moscow, Russia (Phone: 7 095 196 0015; Fax: 7 095 196 0221; E-mail: kholodii@img.ras.ru) 2: Institute of Molecular Genetics, Russian Academy of Sciences, 123182, Moscow, Russia

Publication date: 2002-06-01